1. Field of the Invention
The present invention relates to the growing of seedling plants in plant flats having multiple plant cells each having a drain opening at its lower end. More specifically, the invention relates to a portable power driven apparatus for effecting the simultaneous lifting of multiple plant flats from a lower position engaging trough liquid in an irrigation trough to an elevated position in which bottoms of the flats are spaced above the surface of the trough liquid to effect air pruning of the seedling roots at the drain openings. After a predetermined time period in the elevated position, the apparatus can be activated to the lower position.
2. Related Art
Earlier Todd U.S. Pat. No. 3,667,159 discloses a seedling flat formed of foamed plastic as shown in FIGS. 1 and 2 of said patent in which plant cells 32 are provided with lower openings 34 and are tapered downwardly so that the seedlings can be easily removed from the cell. Seedlings have been grown in such flats with watering being effected by overhead spray means, a procedure that is wasteful of water and can cause disease in the plants. The plant flats of the type disclosed in the Todd patent have been used by positioning their low end in troughs of nutrient containing liquid flows upwardly into the planting cells through the lower openings 34.
It has been previously proposed to provide seedling plants in a plant flat supported on a support from which the plant roots downwardly extend into a floodable trough or the like in which the trough liquid is periodically raised and lowered to provide water and/or nutrients to the roots and to subsequently effect air pruning of the roots. Examples of such devices are found in U.S. Pat. Nos. 3,451,162; 3,925,926; 4,324,069, 4,327,538 and 4,486,977.
It has additionally been proposed for the above noted purpose to provide floating plant flats or the like which float on a body of liquid providing nutrients for plants in the flat as shown in U.S. Pat. Nos. 2,175,113; 2,531,562; 3,927,491; 4,028,847, 4,327,538 and 4,486,977.
It has additionally been proposed for the above noted purpose to provide floating plant flats or the like which float on a body of liquid providing nutrients for plants in the flat as shown in U.S. Pat. Nos. 2,175,113; 2,531,562; 3,927,491; 4,028,847, 4,034,506; 4,037,360; 4,321,152; 4,468,885; and 4,513,533. Additionally, British Patents. Nos. 1,031,309; 1,038,320; 1,053,508; and 1,313,121 also disclosed similar floating plant flat systems.
Another approach has been to provide a trough including fixedly positioned wire means for supporting a plant container such as in U.S. Pat. Nos. 4,075,785 and 4,793,096. Similarly, Austrian Patent No. 241,896 appears to disclose the use of fixed wire supports for plant flats. Other prior art devices of interest include U.S. Pat. Nos. 4,004,369 and 4,166,341.
It is well known in the seedling growing industry to use elongated troughs filled with trough liquid normally comprising nutrient enhanced water. It should be understood that "trough liquid" as used herein is a generic term including plain water or nutrient or chemically enhanced water on which poly-urethane foam plant flats are periodically positioned so that the trough liquid flows upwardly through drain openings in the bottom of plant cell.
While the foregoing operation provides satisfactory results, it also requires the employment of expensive pumps, conduits and storage tanks. Moreover, the conventional systems of the aforementioned type are substantial users of electrical energy.